Faculty Collaboration Database

Cyclic AMP-dependent protein kinase does not increase calcium transport in platelet microsomes. Thromb Res 1989 Dec 01;56(5):575-81

Date

12/01/1989

Pubmed ID

2626742

DOI

10.1016/0049-3848(89)90265-x

Scopus ID

2-s2.0-0024851959 (requires institutional sign-in at Scopus site)   7 Citations

Abstract

Cyclic AMP inhibits platelet activation, at least in part, by reducing intracellular levels of ionic calcium. Previous studies using platelet microsomal fractions have suggested that one mechanism for this effect is stimulation by cyclic AMP and its protein kinase of calcium uptake into microsomal storage sites. In the present study, the effect of cyclic AMP and its protein kinase on calcium uptake by microsomal membranes has been re-examined using the active catalytic subunit of cyclic AMP-dependent protein kinase. The catalytic subunit increased calcium uptake two-fold, but this effect was not inhibited by boiling the catalytic subunit or by recombination with the regulatory subunit of cyclic AMP-dependent protein kinase, conditions that inhibited catalytic subunit activity. Conversely, dialysis of the catalytic subunit preparation against low phosphate buffer, which did not inhibit catalytic subunit activity, inhibited the stimulation of calcium uptake by the catalytic subunit preparation. Finally, the addition of high phosphate buffer, similar in phosphate concentration to that of the catalytic subunit preparation, stimulated calcium uptake. We conclude that the catalytic subunit does not directly stimulate calcium uptake by platelet microsomes.

Author List

White GC 2nd, Barton DW, White TE, Fischer TH

Author

Gilbert C. White MD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Biological Transport
Blood Platelets
Blood Proteins
Calcium
Electrophoresis, Polyacrylamide Gel
Humans
In Vitro Techniques
Microsomes
Phosphorylation
Protein Kinases